A communication channel, whether it is a fiber optic channel, a co-axial channel, a wire channel, a wireless channel, or a bus connecting locations in a system over which large amounts of data are transferred, can add noise and errors to information being transmitted over the channel. To correct for errors added by the communication channel, information can be sent in the form of codewords. In order to improve the performance of digital transmission schemes, coded modulation may be used to jointly optimize coding and modulation.
A variety of schemes for encoding and decoding a codeword for propagation through a communication channel exist. Some schemes may provide accuracy, and other schemes may provide fast decoding. In high speed data communication what is needed is a coded modulation scheme that provides for fast decoding procedures and effective error performance, but at the same time can be implemented without a significant amount of complexity.